A reflection on motor overflow, mirror phenomena, synkinesia and entrainment

In patients with movement disorders, voluntary movements can sometimes be accompanied by unintentional muscle contractions in other body regions. In this review, we discuss clinical and pathophysiological aspects of several motor phenomena including mirror movements, dystonic overflow, synkinesia, entrainment and mirror dystonia, focusing on their similarities and differences. These phenomena share some common clinical and pathophysiological features, which often leads to confusion in their definition. However, they differ in several aspects, such as the body part showing the undesired movement, the type of this movement (identical or not to the intentional movement), the underlying neurological condition, and the role of primary motor areas, descending pathways and inhibitory circuits involved, suggesting that these are distinct phenomena. We summarize the main features of these fascinating clinical signs aiming to improve the clinical recognition and standardize the terminology in research studies. We also suggest that the term “mirror dystonia” may be not appropriate to describe this peculiar phenomenon which may be closer to dystonic overflow rather than to the classical mirror movements

Presynaptic hemiparkinsonism following cerebral toxoplasmosis: case report and literature review

Background: Cerebral toxoplasmosis (CTx) is a CNS opportunistic infection with variable neurological manifestations. While tropism of Toxoplasma gondii for the basal ganglia is well known, movement disorders (MDs) represent only a small percentage of CTx-related neurological complications. CTx-associated MDs are usually hyperkinetic, whereas parkinsonism associated with evidence of presynaptic dopaminergic deficit has never been described. Case: We report an HIV-positive patient who developed a complex MD featuring unilateral tremor combined with parkinsonism and dystonia following an acute episode of disseminated CTx. Her DaTscan documented contralateral presynaptic dopaminergic deficit. Levodopa initiation improved both tremor and parkinsonism after ineffective trials of several other medications over the years. Literature review: A total of 64 patients presenting with CTx-related MDs have been described. The most common MD was chorea (44%), followed by ataxia (20%), parkinsonism (16%), tremor (14%), dystonia (14%), myoclonus (3%) and akathisia (2%). DaTscan was performed only in one case, of Holmes tremor, that demonstrated reduced presynaptic dopaminergic uptake. Positive response to dopaminergic treatment was reported in three cases of Holmes tremor and two of parkinsonism. Conclusions: Presynaptic dopaminergic deficit may occur in CTx-related tremor combined with parkinsonism. Its identification should prompt initiation of levodopa, thus avoiding unnecessary trials of other drugs

Neuropsychiatric Presentation of Anti-DPPX Progressive Encephalomyelitis with Rigidity and Myoclonus

Progressive encephalomyelitis with rigidity and myoclonus (PERM) falls at the severe end of stiff-person-syndrome spectrum disorders, being characterized by brainstem and autonomic involvement in addition to axial and limb rigidity, and central nervous system (CNS) hyperexcitability.1 Autoantibodies against glycine receptor (GlyR) are associated with 70% of PERM cases.2 Other PERM-associated autoantibodies encompass antibodies against glutamic acid decarboxylase (GAD), dipeptidyl peptidase-like-protein-6 (DPPX), and amphiphysin.3 Here, we report an atypical case of anti-DPPX-associated PERM with prominent neuropsychiatric prodrome